-LRB- CNN -RRB- -- Space shuttle Discovery launched just before midnight Friday on a mission to the international space station .

Space shuttle Discovery lifts off late Friday from Kennedy Space Center in a photo from iReporter Alan Walters .

The crew of seven astronauts includes one from Mexico and another from Sweden . One of those seven , Nicole Stott , will remain on the station as a flight engineer , while astronaut Timothy Kopra is to return home aboard the shuttle .

Also on board : The Leonardo logistics module , science experiments and the Combined Operational Load Bearing External Resistance Treadmill -LRB- COLBERT -RRB- , named for fake newsman Stephen Colbert of Comedy Central 's `` The Colbert Report . ''

Colbert won an online poll conducted by NASA to name the newest space station compartment , but Colbert and the space agency compromised to give the moniker to the treadmill . The new compartment was given the name Tranquility .

NASA astronaut Cady Coleman said the treadmill is an essential addition to the space station . Watch shuttle launch ''

`` We have the treadmill now to keep them healthy , which is really part of being able to come home in one piece . So it is an essential part , '' Coleman said . iReport.com : Discovery lights night sky

Discovery 's liftoff , originally set for Tuesday , had been postponed three times -- first for bad weather , and twice more while mission managers checked out indications of a faulty valve .

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Space shuttle Discovery launches just before midnight Friday

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Discovery is scheduled to fly to international space station with a crew of seven

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Logistics module , science experiments , Stephen Colbert treadmill also aboard